Notes: *1) primary and secondary VM has it’s own .vmx and .vmdk file | primary and secondary VM can be placed on different datastores *2) both of these maximums include primary and secondary VMs/vCPUs

But not only limitations have been expanded – there are also other great improvements worth to mention:

In previous versions Fault Tolerance relied on a technology called “Record-Replay” to keep the primary and secondary VM in sync.

With vSphere 6, Fault Tolerance uses a new and more scalable technology: Fast Check-Pointing.

By the way, this new technology was the key to support up to 4 vCPUs!

Another important improvement is the support for vStorage APIs for Data Protection (VADP). With this API it is possible to backup Fault Tolerance VMs using non-disruptive snapshots.

On the storage side a lot has happend, too. Previous FT versions used the same storage for the primary and the secondary VM. Now it is possible to place these two VMs on different datastores to protect both VMs against host and storage failures.

During a Q&A in the Beta Program VMware was asked if FT can be used to protect the vCenter Server.

This is a very interesting question since vCenter Heartbeat is no longer available (end of life since June 2014). The answer was, that VMware is currently testing it – hopefully we will get more information about this soon.